1. Field of the Invention
The present invention relates to line junctions and more particularly to a junction structure connecting a microstrip line and a coplanar transmission line.
2. Description of the Prior Art
In addition to microstrip lines, coplanar transmission lines are also frequently employed in microwave circuits and in circuits of integrated optics, for example for the drive of fast electro-optical waveguide modulators. Both types of lines must often be connected to one another or to coaxial lines by way of broadband junctions. Broadband junctions between rigid coaxial lines and coplanar transmission lines, for example, are well known in the art. The junction from a rigid coaxial cable to, for example, a coplanar line in thin film circuits is technologically difficult, however, because of the required connection of the rigid inner conductor of the coaxial cable to the thin electrode of the coplanar line.
Junctions from coaxial plugs to microstrip lines on Al.sub.2 O.sub.3 are commercially available.